Nice list! I've had a similar experience as you, and many of your bullet points would overlap mine. (And the ones which don't overlap I might learn/steal from you!)
Create a directory where you want the MTGA wine prefix to live (I use /home/my_username/Games/mtg/)
In Lutris, press + to add a new game, and set the following:
Name: "Magic The Gathering Arena"
Runner: Wine
Click Game Options, set the following:
Executable: /path/to/MTGAInstaller.exe
Wine prefix: /path/to/your/wine/prefix/location/ (As I mentioned above, I use /home/my_username/Games/mtg/)
Click Save
Optional, if the game art doesn't auto-populate:
Click Lutris under "Sources" on the left -> Community Installers
Search for "magic arena", and wait for results to populate (the search downloads the art)
Exit the community installer section
Click Play in Lutris
From here it should set up the Wine prefix and install the game. Once that is done then quit the game (if it auto-launches).
Set Lutris to the game's launch executable: right-click on the MTGA icon -> Configure -> Game Options
Executable: /installed/path/to/MTGALauncher.exe (for me it is /home/my_username/Games/mtg/drive_c/Program Files/Wizards of the Coast/MTGA/MTGALauncher/MTGALauncher.exe)
Click Save and you should be good to go!
Good luck! If the game doesn't work following these instructions then you can try running with different versions of Wine (I'm using lutris-GE-Proton8-x86_64). And if it still doesn't work then I'd expect your issue might be with your GPU drivers.
This. Switching to Lubuntu from Windows would be like doubling your RAM because Lubuntu is very lightweight. I'd bet your main problem is running out of RAM.
There have been ads on Kindle for a very long time. You can optionally pay an extra $15-$20 to remove the ads though.